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date: 19 December 2018

Migration and Obesity

Summary and Keywords

There are over 230 million international migrants worldwide, and this number continues to grow. Migrants tend to have limited access to and knowledge about resources and preventative care in their communities of reception, but nonetheless they are often in better health by many measures compared with native-born people in their communities of reception and with the people they left behind at their place of origin. With time since arrival, however, immigrants’ health advantages often dissipate and they experience increases in health problems, especially obesity and diabetes, which are chronic diseases that are increasingly prevalent in the overall population as well and are associated with multiple co-morbidities and limitations. It may be that immigrants have specific health endowments leading to these health patterns, or that the processes involved in migration, including exposure to new environments, behavioral change, and stress of migration may also affect risks of obesity and other chronic conditions. Understanding the health patterns of migrants can be useful in identifying their specific health needs, as well as contributing to our understanding of how specific environments, changes in environments, and individual health endowments interplay to shape the long-term health of populations.

There is considerable political, scholarly, and lay interest in the integration of newly arrived immigrants in Europe and North America, as conflict, poverty, and inequality drive hundreds of thousands of persons each year to look for a better life elsewhere. The successful integration of immigrants is critical for the individuals’ well-being and also for economic advancement and social cohesion in the communities that receive them. A key component of well-being is health (Thomas, 2016). One of the major health concerns that is increasing in prevalence in many parts of the world is obesity, a condition associated with poorer physical and mental health and psychosocial well-being (Division of Nutrition and Physical Activity Nation Center for Chronic Disease Prevention and Health Promotion, 2006; Institute of Medicine, 2005). There is evidence that patterns of chronic disease, including obesity, may be different among migrants compared with native-born people in their communities of reception and compared with the people at their place of origin; it may also be that the processes involved in migration, including exposure to new environments, behavioral change, and stress of migration also affect risks of obesity and other chronic conditions.

Obesity

Obesity is a health condition that is increasing among adults and children in wealthy and poor countries around the world (Black et al., 2013; Division of Nutrition and Physical Activity National Center for Chronic Disease Prevention and Health Promotion; Institute of Medicine, 2005; Patel, Narayan, & Cunningham, 2015; Thomas, 2016). It is intended to refer to excess adiposity, but is typically measured as a body mass index (BMI), calculation of kilograms over meters squared, at or above 30 in adults and a BMI z-score at or above the 95th percentile for age and sex in children. Obesity is a health concern because it is associated with poorer physical and mental health and psychosocial well-being (Division of Nutrition and Physical Activity Nation Center for Chronic Disease Prevention and Health Promotion, 2006; Institute of Medicine, 2005). Levels are particularly high in higher-income countries, but many low- and middle-income countries are experiencing increases in overweight and obesity, even as underweight continues to be a substantial problem (Black et al., 2013; De Onis, Blossner, & Borghi, 2010; Patel et al., 2015). In the United States, a major migrant destination, one in three adults and one in five children and adolescents are obese (Flegal, Carroll, Kit, & Ogden, 2012; Ogden, Carroll, Kit, & Flegal, 2012). Like many other health problems, obesity affects people differently across race-ethnicity and socioeconomic groups: Especially in higher-income countries, poorer and minority people tend to experience higher rates of obesity, and these differences begin to emerge in childhood (Brunner, Chandola, & Marmot, 2007; Burdette & Hill, 2008; Cunningham, Kramer, & Narayan, 2014; Ebelling, Pawlak, & Ludwig, 2002; Goodman et al., 2003; Harding, Teyhan, Maynard, & Cruickshank, 2008; Hedley et al., 2004; Kohl & Hobbs, 1998; Matheson, Moineddin, & Glazier, 2008; Ogden, Carroll, & Flegal, 2008; Pearce, Boergers, & Prinstein, 2002; Plotnikoff, Bercovitz, Rhodes, Loucaides, & Karunamuni, 2007; Sobal & Stunkard, 1989).

International Migration and Health

There are over 230 million international migrants worldwide, and this number continues to grow (UN Department of Economic and Social Affairs, 2013; UNHCR, 2015). People migrate for many reasons, including for work and economic opportunities; family formation; and to escape social, economic, or political hardship (UN Department of Economic and Social Affairs, 2013). About a quarter of them are under the age of 18 years (UNCHR, 2015). Among migrants, almost 16 million are refugees and asylum seekers, who arrive in even more disadvantaged contexts than other immigrants, having lower levels of education, fewer social networks, and poorer health than the overall immigrant population having experienced poor living conditions, food scarcity, and limited access to health care in communities or camps (Chiswick, Lee, & Miller, 2006, 2008; Connolly et al., 2004; Connor, 2010; Potocky-Tripodi, 2003; Takeda, 2000; UNHCR, 2013).

Immigrants are often overrepresented among the groups noted above to be at high risk for obesity: racial and ethnic minorities, those with only high school education, and those living in poverty (Selected Characteristics, 2012). Further, as noted above, studies, especially from English-speaking countries, have indicated that the health of foreign-born people deteriorates with time since migration, especially in terms of obesity and diabetes (Argeseanu Cunningham, 2008; Goel, McCarthy, Phillips, & Wee, 2004; Oza-Frank & Cunningham, 2010; Osypuk, Diez Roux, Hadley, & Kandula, 2009). In a systematic review of immigrant health in the United States, all but one study reported a significant, positive relationship between body weight and duration of residence in the United States (Oza-Frank & Cunningham, 2010). Increases in weight with duration of residence in the United States may be nonlinear, with body weight being observed substantially elevated after 10 to 20 years of residence in the United States (Akresh, 2007; Antecol & Bedard, 2006; Barcenas et al., 2007; Dey & Lucas, 2006; Goel et al., 2004; Himmelgreen et al., 2004; Kaplan et al., 2004; Koya & Egede, 2007; Lauderdale & Rathouz, 2000; Singh & Siahpush, 2002). In Europe and other high-income countries, obesity increases with length of stay have also been indicated among foreign-born people and in their children (Harding et al., 2008; Sniderman, Bhopal, Prabhakaran, Sarrafzadegan, & Tchernof, 2006). The origins of these risks are not well understood; the leading explanations proposed in the literature are summarized below.

Several conceptual models have been proposed to explain the relationships between obesity and migration. Much research, especially in the United States and Canada, has focused on exposure to obesogenic environments, that is, environments that may promote obesity (Akresh, 2007; Antecol & Bedard, 2006; McDonald & Kennedy, 2005). According to this idea, migrant destinations are often places that promote obesity; they have easy access to unhealthy foods; limited access to affordable healthy food options; and both work and leisure opportunities tend to involve sedentary activities, especially sitting in front of a screen. These places have high rates of obesity and other chronic disease among the native-born population, and the longer foreign-born people are exposed to these conditions, the more their weight increases also.

A related explanation for the increases in obesity among immigrants with length of residence focuses on acculturation, or how immigrants’ lifestyles and behaviors change when living in these obesogenic environments. According to this explanation, foreign-born people arrive with different eating and activity habits and preferences, which reflect the healthier environments from which they are coming. These healthier habits are more likely to be retained within ethnic enclaves that can somewhat emulate the environment of origin (McDonald & Kennedy, 2005). With time, however, as immigrants assimilate in terms of language acquisition, jobs, and social factors, they also assimilate in terms of lifestyles relevant to obesity. Immigrants adopt ideas, values, and behaviors that are new and different from their former lifestyles (Lara, Gamboa, Kahramanian, Morales, & Bautista, 2005; Rogler, Cortes, & Malgady, 1991). These changes may include consuming more energy-dense, processed foods and adopting sedentary lifestyles (Akresh, 2007; Gordon-Larsen, Harris, Ward, & Popkin, 2003; Holmboe-Ottesen & Wanderl, 2012; Hunt, Schneider, & Comer, 2004; Jasso, Massey, & Rosenzweig, 2004; Jerome, 1980; Liu, Probst, Harun, Bennett, & Torres, 2009; Shi, van Meijgaard, & Simon, 2012). As a result, after about a decade post arrival into obesogenic environments, foreign-born people have body weights and obesity rates similarly high or even higher than those of the native-born population (Akresh, 2007). This may be particularly the case for immigrants integrating into disadvantaged circumstances, such as bad housing conditions, low income, unemployment, or insecure employment (Ryabov, 2012).

Fewer researchers are also considering the importance of pre-migration exposures and characteristics (Huh, Prause, & Dooley, 2008). One component of this is considering obesity levels in the places of origin of immigrants. In the United States and Europe, many migrants come from Mexico and from North Africa, respectively, places where obesity rates are high. Thus, many people may be arriving into the receiving countries with already high body weights, or may reach high body weights as they age, not as a result of their new environments, but comparable to those of people in their places of origin (Agyemang et al., 2017; Wändell, Carlsson, & Steiner, 2010).

An additional consideration with respect to the place of origin pertains to migrants from origins that are currently experiencing high levels of deprivation, or have a history of deprivation. Migrants from such places may be thin before migrating and on arrival, due to experiences of deprivation (Renzaho, 2004). However, their metabolic systems are programmed for the scarce environments in which they and their ancestors lived. When they encounter the calorie-rich environments of their places of destination, they are not well equipped to handle these environments, and therefore experience rapid increases in obesity and other chronic diseases (Sniderman et al., 2006; Spallek, Zeeb, & Razu, 2011). This hypothesis is sometimes called the adipose tissue overflow hypothesis.

Finally, some researchers have raised the possibility that the process of migration itself may be conducive to obesity (Jasso, Massey, & Rosenzweig, 2004). One reason is the high level of stress experienced by people who are dealing with the hurdles of preparing to migrate, being in transit, and getting established in a new place. This stress may have direct metabolic implications, and may also promote unhealthy coping strategies, such as stress-induced eating, which may lead to obesity. In addition, access to healthy food and physical activity may be limited during the process of migration and resettlement; this may be especially a concern for migrants who spend time in refugee camps or detention facilities. During the early stages of resettlement, migrants may have limited knowledge of where to find the resources they need, such as healthy food or places to walk, especially if they do not know the language in their place of reception or have limited social contacts to help them integrate.

Most of these conceptual models about the relationships between obesity and migration have only been tested empirically to a limited extent, and research is still underway to determine the relative importance of each, and how this varies across context of origin and of reception. Understanding the role of the environments of origin and of reception and those of individual endowments and experiences has applied implications; for example, if the place of origin and early life experiences are particularly important, then programs can focus on prevention efforts among the vulnerable groups; if exposures at the place of resettlement are most pertinent, then high-risk places should be the focus for programs, not only for immigrants but also for native-born people living in these places.

As a final note, research on patterns of obesity in immigrant children is still in its infancy and results are inconclusive. One U.S.-based study reported that overweight and obesity prevalence was lower for immigrant Black and White children compared with native-born children of the same groups, but that there were no differences by place of birth for Hispanic children (Singh, Kogan, & Yu, 2009). Another study found that Hispanic children of foreign-born parents were heavier than non-Hispanic White children of U.S.-born parent (Moving to the Land of Milk and Cookies, 2009). A European overview found higher obesity levels in children of North African immigrants than the native children of both sexes, especially in females. Body image perception, Westernization of food habits, and lack of physical activity are pinpointed as contributing factors (Gualdi-Russo et al., 2014). Qualitative research can add further insights into these scenarios of integration, for example, providing different perspectives of how values about body size ideals and body image change.

Discussion

The health of the world’s almost 2.5 million international migrants is an important consideration for health care professionals, officials, and scholars. In spite of limited knowledge and access, migrants are often initially in better health by many measures compared with native-born people in their communities of reception and with the people they left behind at their place of origin. With time since migration, however, immigrants experience increases in health problems, especially obesity and diabetes. Research has identified several possible reasons for these health patterns: it may be that immigrants have different health endowments, perhaps which are characteristics associated with their propensity to migrate; it may be that the processes involved in migration, including exposure to new environments, behavioral change, and stress of migration may also affect risks of obesity and other chronic conditions.

Despite the development of several explanatory models linking migration to obesity, the underlying mechanisms largely remain unclear, due to a lack of data, for example, of cohort studies of migrants, particularly in Europe. To enhance migrant obesity research, an important step will be to adopt a life course perspective and to take into account pre-, per- and post- migratory factors, as well as the health status of host and home country populations (Agyemang et al., 2017; Spallek, Zeeb, & Razu, 2011).

Qualitative research will be useful for several aspects of research on migration and obesity. Because of the cultural and linguistic diversity of migrant populations, it is particularly important to use qualitative methods in the development of large-scale quantitative instruments, including cognitive interviews and semi-structured interviews to identify appropriate questions, terms and phrases, and areas of particular salience to explore. In addition, qualitative studies offer the advantage of being more accessible to communication with participants with diverse language backgrounds. For example, methods such as free-listing and pile-sorting methods, photovoice, and non-participatory observations are receiving interest from researchers to learn about aspects of the migration experience that are not easily captured through questionnaires. Qualitative methods such as in-depth interviews also can provide insights into the lived experiences of migrants.

High-quality, multi-method studies are needed, because the observed patterns of migrant health are complex. Factors, such as childhood deprivation in the home country (pre-migration experience), stress during migration (per-migration experience), as well as the obesity levels of the host populations in the respective countries of settlement (post-migration experience), may play a part. These pre-, per- and post-migratory factors and the interaction between them have not yet been well captured in epidemiological research. Cohort studies could provide valuable insights (Agyemang et al., 2012). Extending migrant obesity research across national borders by comparing migrant populations with similar populations in the home country that are left behind and/or by comparing similar migrant populations across different high-income settlement countries, would be another way of enhancing epidemiological research on migration and obesity. Comparison with the left behind population allows for investigating the role of migration on obesity, while comparison between different settlement countries assesses the role different national contexts may play (Bhopal et al., 2012). This approach could allow us to pinpoint more closely the factors at play.

Examining how newly arrived immigrants adopt ideas, values, and behaviors that can change their risks of developing obesity can be an approach to understanding and addressing inequalities in health. Immigrants’ oft-disadvantaged position in society can have an impact on their health, as can the political and societal context they live in, such as the health system, integration policies, public attitudes toward migration, and racism (Solar, 2010). More broadly, understanding the health patterns of migrants can be useful in identifying their specific health needs, as well as contributing to our understanding of how specific environments, changes in environments, and individual health endowments intersect to shape the long-term health of populations.

Further Reading

Agyemang, C., Owusu-Dabo, E., de Jonge, A., Martins, D., Ogedegbe, G., & Stronks, K. (2009). Overweight and obesity among Ghanaian residents in the Netherlands: How do they weigh against their urban and rural counterparts in Ghana? Public Health Nutrition, 12, 909–916.Find this resource:

Lauderdale, D. S., & Rathouz, P. J. (2000). Body mass index in a U.S. national sample of Asian Americans: Effects of nativity, years since immigration and socioeconomic status. International Journal of Obesity and Related Metabolic Disorders, 24, 1188–1194.Find this resource:

Himmelgreen, D. A., Perez-Escamilla, R., Martinez, D., Bretnall, A., Eells, B., Peng, Y., & Bermúdez, A. (2004). The longer you stay, the bigger you get: Length of time and language use in the U.S. are associated with obesity in Puerto Rican women. American Journal of Physical Anthropology, 125, 90–96.Find this resource:

Hunt, L. M., Schneider, S., & Comer, B. (2004). Should “acculturation” be a variable in health research? A critical review of research on U.S. Hispanics. Social Science & Medicine, 59, 973–986.Find this resource:

Koya, D. L., & Egede, L. E. (2007). Association between length of residence and cardiovascular disease risk factors among an ethnically diverse group of United States immigrants. Journal of General Internal Medicine, 22, 841–846.Find this resource:

Landale, N. S., Thomas, K. J., & Van Hook, J. (2011). The living arrangements of children of immigrants. The future of children/Center for the Future of Children, the David and Lucile Packard Foundation, 21, 43–70.Find this resource:

Lauderdale, D. S., & Rathouz, P.J. (2000). Body mass index in a U.S. national sample of Asian Americans: Effects of nativity, years since immigration and socioeconomic status. International Journal of Obesity and Related Metabolic Disorders, 24, 1188–1194.Find this resource:

Ogden, C. L., Carroll, M. D., & Flegal, K. M. (2008). High body mass index for age among U.S. children and adolescents, 2003–2006. Journal of the American Medical Association, 299, 2401–2405.Find this resource: